Yasha Neiman

Research Interests

The grand project of unifying quantum mechanics with gravity has seen great progress in the last two decades. Through holography, we have a good grasp of quantum-gravitational theories that deal with observables at spatial infinity in a world with negative cosmological constant. The next task is to bring this picture closer to the real world, where the cosmological constant is positive, and infinity is inaccessible due to causal horizons. This is the aim of dS/CFT - holography in de Sitter space.
The one existing model for dS/CFT in a world of realistic dimension (3+1) involves a more symmetric cousin of General Relativity, known as higher-spin gravity. This model allows one to compute a preferred state for the quantum-gravitational universe in the infinite past or future. However, it isn't clear how to extract dynamics, and in any case such a state of the entire universe is unobservable, due to the same horizons that make de Sitter space interesting in the first place.
The goal of my research is to take the higher-spin dS/CFT away from non-evolving global states, and towards constructing states and dynamics within the horizons of realistic observers. A key step is to "fold the spacetime in half" in such a way that the fields at infinity, described by standard dS/CFT, become causally equivalent to those in an observer's causal patch. This "folding in half" appears to be especially compatible with higher-spin theory. If successful, this line of work will provide the first description of a quantum-gravitational system from the point of view of observers who are confined inside horizons, as is the case for all observers in real-world cosmology.

Positions Held

2012-2014 Institute for Gravitation and the Cosmos & Department of Physics, Pennsylvania State University
Postdoctoral Researcher